Injection of botulinum toxin and results in patients with thyroid orbitopathy with upper eyelid retraction, evaluation of factors affecting the results

Purpose: This study aims to compare the clinical outcomes of botulinum toxin A (BoTA) injections for the treatment of upper eyelid retraction (ULR) secondary to thyroid orbitopathy (TO), investigate the efficacy level of BoTA and the factors affecting the efficacy level. Materials and Methods: The records of 52 eyes of 34 patients who were admitted to Akdeniz University Hospital Ophthalmology Clinic between May 2022 and October 2023 with ULR due to TO and who underwent BoTA injection treatment to the levator muscle were retrospectively analysed. Mild and moderate-severe subgroups were subdivided according to the level of retraction. Demographic characteristics of the patients, palpebral fissure height, clinical activity score (CAS), thyroid function test (TFT) measurements and factors affecting the treatment were recorded at the pre-injection (PrI) and post-injection (PsI) 2nd week, 1st, 3rd and 6th month examinations. Results: Fifty-two eyes of 34 patients, 24 female (70.5%) and 10 male (29.4%), with a mean age of 48.56 years, were included in the study. Among the patients, 19 patients were euthyroid. 21 (40.3%) of 52 eyes had mild (40.3%) and 31 (59.6%) eyes had moderate-severe ULR. MRD1 values were found to be significantly lower in mild and moderate-severe cases at the 2nd week and 1st month of post-injection (PsI), and compared to the 6th month of PsI and pre-injection (PrI). Nasal palpebral fissure height (NPFH) and central palpebral fissure height (SPFH) values were significantly lower in mild and moderate-severe stages at the 2nd week, 1st month and 3rd month of PsI compared to PrI, and at the 2nd week and 1st month of PsI compared to 6th month of PsI. Temporal palpebral fissure height (TPFH) values were found to be significantly lower in mild stages at the 2nd week and 1st month of PsI values, compared to the 6th month of PsI and PrI values, and 3rd month of PsI values compared to PrI. In cases with moderate-severe stages of TPFH, at the 2nd week, 1st month and 3rd month of PsI values were significantly lower than PrI and 6th month of PsI; 1st month and 3rd month of PsI MRD2 values were significantly lower than PrI. In the mild and moderate-severe stage subgroups, CAS was found to be significantly lower at the 1st month of PsI compared to PrI. In the PsI follow-up, it was determined that those who had never had elevated CPFH and TPFH values compared to PrI were predominantly euthyroid, whereas those who had elevated CPFH and TPFH values at the 6th month of PsI were predominantly non-euthyroid. No statistically significant correlation was found between the presence of PrI lidlag, smoking status, radioactive iodine (RAI) treatment, medical treatment of thyroid, duration of thyroid disease, mild or moderate-severe stage and treatment response (p>0.05). It was concluded that the efficacy of BoTA injection in the treatment of ULR was sustained in 65% of the patients (34 eyes). Discussion and Conclusions: BoTA injection results are more stable in euthyroid patients. While antithyroid treatment response is expected in dysthyroid patients, BoTA injection reduces conjunctival hyperemia by decreasing the palpebral fissure height in the treatment of ULR and should be considered in the secondary treatment of dry eye. Keywords: Thyroid orbitopathy, botulinum toxin A, upper eyelid retraction.